How to create a unique string for use in designer script?

To create and store an unique string, add the following entry in the designer script:

Action: Store

Accessor: dyn1

Value: eval('\"Appvance\" + Math.floor(Math.random()*100)')

Now the value that is saved in 'dyn1', can be used as an input to textbox etc.

Action: setValue

Accessor: textbox("Building.name"), storedVars["dyn1"]